In-plane oval-twisted spiral tube heat exchanger for nuclear applications

This paper investigated the concept of using the oval-twisted tube to enhance the heat transfer performance for advanced passive HX applications. The oval-twisted geometry is proposed for spiral tube HX. The performance is compared to circular and oval spiral tube HX. The analysis investigated the effects of oval AR (1.38-2) and Ro (72.5-97 mm) on the Nu and ff over the laminar flow (De = 50 to 1050) and constant surface temperature conditions. The results showed that the oval-twisted spiral tube HX provides higher Nu compared to circular and oval spiral tube HX at an equivalent level of f over the range of investigated De for AR = 1.38. The AR has no effects on the Nu and f for the oval spiral but increases the Nu and f for the oval-twisted spiral tube HX. At AR of 2, the oval-twisted spiral tube shows ~9 to 28% increase in the Nu and ~14 to 38% increase for the The oval-twisted spiral tube HX with an AR of 2 showed consistent and stable Nuand f results for Ro = 72.5 to 97 mm. These results demonstrate that the oval-twisted spiral tube geometry can accommodate any possible thermal expansion by taking advantage of the spring-like shape without impacting the HX performance. This study presented the proof of concept (computationally) of in-plane oval-twisted spiral tube oval twisted tube geometry to enhance heat transfer over other circular and oval spiral tube geometries. The simulation work will continue modeling an entire HX device under laminar and turbulent flow conditions, using different fluids to adapt to various advanced reactor coolants' needs. The flow-induced vibration and thermal-structure analysis will be studied in future research.